The present invention relates to a new and improved construction of an objective possessing variable focal length with and aperture ratio of about 1:1.0 to 1:14.4 for narrow film projectors and microscopes comprising at least six lens members separated by air spaces or gaps.
The objective of this invention is an improvement upon the varifocal objective disclosed in my U.S. Pat. No. 3,466,113, granted Sept. 9, 1969. Experiments carried out on the objective constructions disclosed in the aforementioned U.S. patent have shown that with the aid of simple means, such as incorporating a lens member which faces towards the film or towards the shorter conjugate, completely new possibilities can be realized. It is from this basic concept that the present invention evolved.